Education Minister Jan O'Sullivan is under fire on two fronts after announcing plans to loosen the grip of religion on primary education - and abandoning moves to reform school admissions' rules.

Catholic bishops have warned the minister against interfering with the ethos of faith-based schools in the wake of her decision to abolish a rule about the place of religion in primary education.

She said she would get rid of the "archaic" 50-year-old Rule 68 which stipulates a religious spirit must inform the work of faith schools, which means that its influence extends beyond formal religion classes. The minister said the rule would go in January.

It sparked a strong reaction from the Catholic Church with Bishop Brendan Kelly, secretary of the Bishops' Council for Education, stating it was "not the role of the minister to determine or interfere with the ethos of faith schools".

Fr Tom Deenihan, general secretary of the Catholic Primary School Management Association (CPSMA) expressed concern that there was an intention to remove the denominational ethos from the education system and said it could "create a school system that is generic in terms of curriculum, where patronage makes no difference.

"I ask the minister to give an undertaking that denominational schools, of whatever persuasion, be allowed to teach religious education during the school day in accordance with the school's ethos," he said.

Meanwhile, Ms O'Sullivan was accused of "retreating to the political trenches" after accepting that the long-awaited Schools Admission Bill will not get over the line in the current Dáil.

She was forced to defend her decision to effectively shelve plans that would prevent schools from reserving any more than one-in-10 places for the children of past pupils.

Curbs on the number of places that a school could reserve for children of past pupils was one of the measures envisaged in the proposed legislation, which was aiming to make admissions fairer and more transparent.

She denied "kicking the Bill to touch", claiming there is "no doubt" that the Admissions Bill will go through the Oireachtas after the election "because it has to".

However, Fianna Fáil's Charlie McConalogue said she was "being defeatist rather than realistic because this is something which was very much within the minister's grasp".

He said schools admission is one of the key issues, along with junior certificate reform and divestment, which the minister and her predecessor had flagged as "priorities for the Labour Party in government and on each of those fronts we have seen a total failure to deliver in any meaningful way, or certainly in the way that was outlined".